102 ideas
| 2512 | Philosophy is a battle against the bewitchment of our intelligence by means of language [Wittgenstein] |
| Full Idea: Philosophical problems are solved, not by giving new information, but by arranging what we have already known. Philosophy is a battle against the bewitchment of our intelligence by means of language. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §109), quoted by Jerrold J. Katz - Realistic Rationalism Int.xi | |
| A reaction: A philosophical dispute can be settled by a piece of information, which may be already known to you, but new to me. Philosophical discussion can also point to a scientific research programme - i.e. a need for new information. I like the first sentence. |
| 4148 | What is your aim in philosophy? - To show the fly the way out of the fly-bottle [Wittgenstein] |
| Full Idea: What is your aim in philosophy? - To show the fly the way out of the fly-bottle. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §309) | |
| A reaction: Ridiculous. Trying to think about thought is not a pointless buzzing - it is an attempt by humans to become like gods. |
| 22490 | Bring words back from metaphysics to everyday use [Wittgenstein] |
| Full Idea: What we do is to bring words back from their metaphysical to their everyday use. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], 116), quoted by Philippa Foot - Natural Goodness 7 n16 | |
| A reaction: A germ of ordinary language philosophy. It is wrong to think that metaphysics must be studied in the usages of ordinary language, but I strongly believe that words like 'essence' or 'objectivity' should retain their normal meaning when philosophising. |
| 16325 | Analysis rests on natural language, but its ideal is a framework which revises language [Halbach] |
| Full Idea: For me, although the enterprise of philosophical analysis is driven by natural language, its goal is not a linguistic analysis of English but rather an expressively strong framework that may at best be seen as a revision of English. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 12) | |
| A reaction: I agree, but the problem is that there are different ideals for the revision, which may be in conflict. Logicians, mathematicians, metaphysicians, scientists, moralists and aestheticians are queueing up to improve in their own way. |
| 6566 | The problem is to explain the role of contradiction in social life [Wittgenstein] |
| Full Idea: When a contradiction appears, we say: "I didn't mean it like that"; the civil status of a contradiction, or its status in civil life: there is the philosophical problem. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §125), quoted by Robert Fogelin - Walking the Tightrope of Reason Ch.2 | |
| A reaction: The point is that logical concepts such as contradiction are conventional, and not all-or-nothing, so we might agree that you didn't really contradict yourself (when perhaps you uttered a witty ironic paradox). I don't see the problem as philosophical. |
| 16292 | An explicit definition enables the elimination of what is defined [Halbach] |
| Full Idea: Explicit definitions allow for a complete elimination of the defined notion (at least in extensional contexts). | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 1) | |
| A reaction: If the context isn't extensional (concerning the things themselves) then we could define one description of it, but be unable to eliminate it under another description. Elimination is no the aim of an Aristotelian definition. Halbach refers to truth. |
| 16307 | Don't trust analogies; they are no more than a guideline [Halbach] |
| Full Idea: Arguments from analogy are to be distrusted: at best they can serve as heuristics. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 4) |
| 16339 | Truth axioms prove objects exist, so truth doesn't seem to be a logical notion [Halbach] |
| Full Idea: Two typed disquotation sentences, truth axioms of TB, suffice for proving that there at least two objects. Hence truth is not a logical notion if one expects logical notions to be ontologically neutral. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 21.2) |
| 16330 | Truth-value 'gluts' allow two truth values together; 'gaps' give a partial conception of truth [Halbach] |
| Full Idea: Truth-value 'gluts' correspond to a so-called dialethic conception of truth; excluding gluts and admitting only 'gaps' leads to a conception of what is usually called 'partial' truth. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 15.2) | |
| A reaction: Talk of 'gaps' and 'gluts' seem to be the neatest way of categorising views of truth. I want a theory with no gaps or gluts. |
| 16324 | Any definition of truth requires a metalanguage [Halbach] |
| Full Idea: It is plain that the distinction between object and metalanguage is required for the definability of truth. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 11) | |
| A reaction: Halbach's axiomatic approach has given up on definability, and therefore it can seek to abandon the metalanguage and examine 'type-free' theories. |
| 16293 | Traditional definitions of truth often make it more obscure, rather than less [Halbach] |
| Full Idea: A common complaint against traditional definitional theories of truth is that it is far from clear that the definiens is not more in need of clarification than the definiendum (that is, the notion of truth). | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 1) | |
| A reaction: He refers to concepts like 'correspondence', 'facts', 'coherence' or 'utility', which are said to be trickier to understand than 'true'. I suspect that philosophers like Halbach confuse 'clear' with 'precise'. Coherence is quite clear, but imprecise. |
| 16301 | If people have big doubts about truth, a definition might give it more credibility [Halbach] |
| Full Idea: If one were wondering whether truth should be considered a legitimate notion at all, a definition might be useful in dispersing doubts about its legitimacy. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 3) | |
| A reaction: Halbach is proposing to skip definitions, and try to give rules for using 'true' instead, but he doesn't rule out definitions. A definition of 'knowledge' or 'virtue' or 'democracy' might equally give those credibility. |
| 16297 | Semantic theories avoid Tarski's Theorem by sticking to a sublanguage [Halbach] |
| Full Idea: In semantic theories (e.g.Tarski's or Kripke's), a definition evades Tarski's Theorem by restricting the possible instances in the schema T[φ]↔φ to sentences of a proper sublanguage of the language formulating the equivalences. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 1) | |
| A reaction: The schema says if it's true it's affirmable, and if it's affirmable it's true. The Liar Paradox is a key reason for imposing this restriction. |
| 16337 | Disquotational truth theories are short of deductive power [Halbach] |
| Full Idea: The problem of restricted deductive power has haunted disquotational theories of truth (…because they can't prove generalisations). | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 19.5) |
| 16326 | The main semantic theories of truth are Kripke's theory, and revisions semantics [Halbach] |
| Full Idea: Revision semantics is arguably the main competitor of Kripke's theory of truth among semantic truth theories. …In the former one may hope through revision to arrive at better and better models, ..sorting out unsuitable extensions of the truth predicate. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 14) | |
| A reaction: Halbach notes later that Kripke's theory (believe it or not) is considerably simpler than revision semantics. |
| 16299 | Gödel numbering means a theory of truth can use Peano Arithmetic as its base theory [Halbach] |
| Full Idea: Often syntactic objects are identified with their numerical codes. …Expressions of a countable formal language can be coded in the natural numbers. This allows a theory of truth to use Peano Arithmetic (with its results) as a base theory. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 2) | |
| A reaction: The numbering system is the famous device invented by Gödel for his great proof of incompleteness. This idea is a key to understanding modern analytic philosophy. It is the bridge which means philosophical theories can be treated mathematically. |
| 16340 | Truth axioms need a base theory, because that is where truth issues arise [Halbach] |
| Full Idea: Considering the truth axioms in the absence of a base theory is not very sensible because characteristically truth theoretic reasoning arises from the interplay of the truth axioms with the base theory. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 21.2) | |
| A reaction: The base theory usually seems to be either Peano arithmetic or set theory. We might say that introverted thought (e.g. in infants) has little use for truth; it is when you think about the world that truth becomes a worry. |
| 16305 | We know a complete axiomatisation of truth is not feasible [Halbach] |
| Full Idea: In the light of incompleteness phenomena, one should not expect a categorical axiomatisation of truth to be feasible, but this should not keep one from studying axiomatic theories of truth (or of arithmetic). | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 3) | |
| A reaction: This, of course, is because of Gödel's famous results. It is important to be aware in this field that there cannot be a dream of a final theory, so we are just seeing what can be learned about truth. |
| 16311 | To axiomatise Tarski's truth definition, we need a binary predicate for his 'satisfaction' [Halbach] |
| Full Idea: If the clauses of Tarski's definition of truth are turned into axioms (as Davidson proposed) then a primitive binary predicate symbol for satisfaction is needed, as Tarski defined truth in terms of satisfaction. Standard language has a unary predicate. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 5.2) |
| 16313 | A theory is 'conservative' if it adds no new theorems to its base theory [Halbach, by PG] |
| Full Idea: A truth theory is 'conservative' if the addition of the truth predicate does not add any new theorems to the base theory. | |
| From: report of Volker Halbach (Axiomatic Theories of Truth [2011], 6 Df 6.6) by PG - Db (ideas) | |
| A reaction: Halbach presents the definition more formally, and this is my attempt at getting it into plain English. Halbach uses Peano Arithmetic as his base theory, but set theory is also sometimes used. |
| 16315 | The Tarski Biconditional theory TB is Peano Arithmetic, plus truth, plus all Tarski bi-conditionals [Halbach] |
| Full Idea: The truth theory TB (Tarski Biconditional) is all the axioms of Peano Arithmetic, including all instances of the induction schema with the truth predicate, plus all the sentences of the form T[φ] ↔ φ. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 7) | |
| A reaction: The biconditional formula is the famous 'snow is white' iff snow is white. The truth of the named sentence is equivalent to asserting the sentence. This is a typed theory of truth, and it is conservative over PA. |
| 16318 | Compositional Truth CT has the truth of a sentence depending of the semantic values of its constituents [Halbach] |
| Full Idea: In the typed Compositional Truth theory CT, it is compositional because the truth of a sentence depends on the semantic values of the constituents of that sentence. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 8) | |
| A reaction: [axioms on p. 65 of Halbach] |
| 16322 | CT proves PA consistent, which PA can't do on its own, so CT is not conservative over PA [Halbach] |
| Full Idea: Compositional Truth CT proves the consistency of Peano arithmetic, which is not provable in Peano arithmetic by Gödel's second incompleteness theorem. Hence the theory CT is not conservative over Peano arithmetic. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 8.6) |
| 16314 | Theories of truth are 'typed' (truth can't apply to sentences containing 'true'), or 'type-free' [Halbach] |
| Full Idea: I sort theories of truth into the large families of 'typed' and 'type-free'. Roughly, typed theories prohibit a truth predicate's application to sentences with occurrences of that predicate, and one cannot prove the truth of sentences containing 'true'. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], II Intro) | |
| A reaction: The problem sentence the typed theories are terrified of is the Liar Sentence. Typing produces a hierarchy of languages, referring down to the languages below them. |
| 16294 | Axiomatic truth doesn't presuppose a truth-definition, though it could admit it at a later stage [Halbach] |
| Full Idea: Choosing an axiomatic approach to truth might well be compatible with the view that truth is definable; the definability of truth is just not presupposed at the outset. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 1) | |
| A reaction: Is it possible that a successful axiomatisation is a successful definition? |
| 16327 | Friedman-Sheard is type-free Compositional Truth, with two inference rules for truth [Halbach] |
| Full Idea: The Friedman-Sheard truth system FS is based on compositional theory CT. The axioms of FS are obtained by relaxing the type restriction on the CT-axioms, and adding rules inferring sentences from their truth, and vice versa. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 15) | |
| A reaction: The rules are called NEC and CONEC by Halbach. The system FSN is FS without the two rules. |
| 16331 | The KF is much stronger deductively than FS, which relies on classical truth [Halbach] |
| Full Idea: The Kripke-Feferman theory is relatively deductively very strong. In particular, it is much stronger than its competitor FS, which is based on a completely classical notion of truth. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 15.3) |
| 16329 | Kripke-Feferman theory KF axiomatises Kripke fixed-points, with Strong Kleene logic with gluts [Halbach] |
| Full Idea: The Kripke-Feferman theory KF is an axiomatisation of the fixed points of an operator, that is, of a Kripkean fixed-point semantics with the Strong Kleene evaluation schema with truth-value gluts. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 15.1) |
| 16332 | The KF theory is useful, but it is not a theory containing its own truth predicate [Halbach] |
| Full Idea: KF is useful for explicating Peano arithmetic, but it certainly does not come to close to being a theory that contains its own truth predicate. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 16) | |
| A reaction: Since it is a type-free theory, its main philosophical aspiration was to contain its own truth predicate, so that is bad news (for philosophers). |
| 16320 | Some say deflationism is axioms which are conservative over the base theory [Halbach] |
| Full Idea: Some authors have tried to understand the deflationist claim that truth is not a substantial notion as the claim that a satisfactory axiomatisation of truth should be conservative over the base theory. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 8) |
| 16338 | Deflationism says truth is a disquotation device to express generalisations, adding no new knowledge [Halbach] |
| Full Idea: There are two doctrines at the core of deflationism. The first says truth is a device of disquotation used to express generalisations, and the second says truth is a thin notion that contributes nothing to our knowledge of the world | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 21) |
| 16316 | Deflationists say truth is just for expressing infinite conjunctions or generalisations [Halbach] |
| Full Idea: Deflationists do not hold that truth is completely dispensable. They claim that truth serves the purpose of expressing infinite conjunctions or generalisations. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 7) | |
| A reaction: It is also of obvious value as a shorthand in ordinary conversation, but rigorous accounts can paraphrase that out. 'What he said is true'. 'Pick out the true sentences from p,q,r and s' seems to mean 'affirm some of them'. What does 'affirm' mean? |
| 16317 | The main problem for deflationists is they can express generalisations, but not prove them [Halbach] |
| Full Idea: The main criticism that deflationist theories based on the disquotation sentences or similar axioms have to meet was raised by Tarski: the disquotation sentences do not allow one to prove generalisations. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 7) |
| 16319 | Compositional Truth CT proves generalisations, so is preferred in discussions of deflationism [Halbach] |
| Full Idea: Compositional Truth CT and its variants has desirable generalisations among its logical consequences, so they seem to have ousted purely disquotational theories such as TB in the discussion on deflationism. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 8) |
| 16335 | In Strong Kleene logic a disjunction just needs one disjunct to be true [Halbach] |
| Full Idea: In Strong Kleene logic a disjunction of two sentences is true if at least one disjunct is true, even when the other disjunct lacks a truth value. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 18) | |
| A reaction: This sounds fine to me. 'Either I'm typing this or Homer had blue eyes' comes out true in any sensible system. |
| 16334 | In Weak Kleene logic there are 'gaps', neither true nor false if one component lacks a truth value [Halbach] |
| Full Idea: In Weak Kleene Logic, with truth-value gaps, a sentence is neither true nor false if one of its components lacks a truth value. A line of the truth table shows a gap if there is a gap anywhere in the line, and the other lines are classical. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 18) | |
| A reaction: This will presumably apply even if the connective is 'or', so a disjunction won't be true, even if one disjunct is true, when the other disjunct is unknown. 'Either 2+2=4 or Lot's wife was left-handed' sounds true to me. Odd. |
| 16309 | Every attempt at formal rigour uses some set theory [Halbach] |
| Full Idea: Almost any subject with any formal rigour employs some set theory. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 4.1) | |
| A reaction: This is partly because mathematics is often seen as founded in set theory, and formal rigour tends to be mathematical in character. |
| 16333 | The underestimated costs of giving up classical logic are found in mathematical reasoning [Halbach] |
| Full Idea: The costs of giving up classical logic are easily underestimated, …the price being paid in terms of mathematical reasoning. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 16.2) | |
| A reaction: No one cares much about such costs, until you say they are 'mathematical'. Presumably this is a message to Graham Priest and his pals. |
| 18743 | Wittgenstein says we want the grammar of problems, not their first-order logical structure [Wittgenstein, by Horsten/Pettigrew] |
| Full Idea: For the later Wittgenstein what we should be after is the grammatical structure of philosophical problems, not the first-order logical structure of such problems. | |
| From: report of Ludwig Wittgenstein (Philosophical Investigations [1952]) by Horsten,L/Pettigrew,R - Mathematical Methods in Philosophy 2 | |
| A reaction: This is the most sympathetic spin I have ever seen put on the apparent rather anti-philosophical later Wittgenstein. I nurse doubts about highly formal approaches to philosophy, and maybe 'grammar' (whatever that is) is our target. |
| 16310 | A theory is some formulae and all of their consequences [Halbach] |
| Full Idea: A theory is a set of formulae closed under first-order logical consequence. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 5.1) |
| 4139 | Naming is a preparation for description [Wittgenstein] |
| Full Idea: Naming is a preparation for description. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §049) | |
| A reaction: Something has to be the starting point for a description. And yet a description could turn out to be an elaborate name. |
| 4946 | A name is not determined by a description, but by a cluster or family [Wittgenstein, by Kripke] |
| Full Idea: According to Wittgenstein (and Searle) the referent of a name is determined not by a single description but by some cluster or family. | |
| From: report of Ludwig Wittgenstein (Philosophical Investigations [1952], §079) by Saul A. Kripke - Naming and Necessity lectures Lecture 1 | |
| A reaction: It is because of this characteristically woolly, indeterminate and relativist view of Wittgenstein that I (and most people) find Kripke's notion of a 'baptism' so refreshing. It cuts throught the fog of language, and connects to reality. |
| 16341 | Normally we only endorse a theory if we believe it to be sound [Halbach] |
| Full Idea: If one endorses a theory, so one might argue, one should also take it to be sound. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 22.1) |
| 16344 | Soundness must involve truth; the soundness of PA certainly needs it [Halbach] |
| Full Idea: Soundness seems to be a notion essentially involving truth. At least I do not know how to fully express the soundness of Peano arithmetic without invoking a truth predicate. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 22.1) | |
| A reaction: I suppose you could use some alternative locution such as 'assertible' or 'cuddly'. Intuitionists seem a bit vague about the truth end of things. |
| 16342 | You cannot just say all of Peano arithmetic is true, as 'true' isn't part of the system [Halbach] |
| Full Idea: One cannot just accept that all the theorems of Peano arithmetic are true when one accepts Peano arithmetic as the notion of truth is not available in the language of arithmetic. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 22.1) | |
| A reaction: This is given as the reason why Kreisel and Levy (1968) introduced 'reflection principles', which allow you to assert whatever has been proved (with no mention of truth). (I think. The waters are closing over my head). |
| 16347 | Many new paradoxes may await us when we study interactions between frameworks [Halbach] |
| Full Idea: Paradoxes that arise from interaction of predicates such as truth, necessity, knowledge, future and past truths have receive little attention. There may be many unknown paradoxes lurking when we develop frameworks with these intensional notions. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 24.2) | |
| A reaction: Nice. This is a wonderful pointer to new research in the analytic tradition, in which formal problems will gradually iron out our metaphysical framework. |
| 16336 | The liar paradox applies truth to a negated truth (but the conditional will serve equally) [Halbach] |
| Full Idea: An essential feature of the liar paradox is the application of the truth predicate to a sentence with a negated occurrence of the truth predicate, though the negation can be avoided by using the conditional. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 19.3) |
| 16321 | The compactness theorem can prove nonstandard models of PA [Halbach] |
| Full Idea: Nonstandard models of Peano arithmetic are models of PA that are not isomorphic to the standard model. Their existence can be established with the compactness theorem or the adequacy theorem of first-order logic. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 8.3) |
| 16343 | The global reflection principle seems to express the soundness of Peano Arithmetic [Halbach] |
| Full Idea: The global reflection principle ∀x(Sent(x) ∧ Bew[PA](x) → Tx) …seems to be the full statement of the soundness claim for Peano arithmetic, as it expresses that all theorems of Peano arithmetic are true. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 22.1) | |
| A reaction: That is, an extra principle must be introduced to express the soundness. PA is, of course, not complete. |
| 16312 | To reduce PA to ZF, we represent the non-negative integers with von Neumann ordinals [Halbach] |
| Full Idea: For the reduction of Peano Arithmetic to ZF set theory, usually the set of finite von Neumann ordinals is used to represent the non-negative integers. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 6) | |
| A reaction: Halbach makes it clear that this is just one mode of reduction, relative interpretability. |
| 16308 | Set theory was liberated early from types, and recent truth-theories are exploring type-free [Halbach] |
| Full Idea: While set theory was liberated much earlier from type restrictions, interest in type-free theories of truth only developed more recently. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 4) | |
| A reaction: Tarski's theory of truth involves types (or hierarchies). |
| 16345 | That Peano arithmetic is interpretable in ZF set theory is taken by philosophers as a reduction [Halbach] |
| Full Idea: The observation that Peano arithmetic is relatively interpretable in ZF set theory is taken by many philosophers to be a reduction of numbers to sets. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 23) | |
| A reaction: Nice! Being able to express something in a different language is not the same as a reduction. Back to the drawing board. What do you really mean by a reduction? If we model something, we don't 'reduce' it to the model. |
| 15106 | Essence is expressed by grammar [Wittgenstein] |
| Full Idea: Essence is expressed by grammar. ...Grammar tells us what kind of object anything is. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §371-3) | |
| A reaction: Enigmatic, as usual. The second part seems to imply sortal essentialism, though the emphasis on grammar seems to make it highly conventional, rather than a reflection of 'real' sorts. |
| 16346 | Maybe necessity is a predicate, not the usual operator, to make it more like truth [Halbach] |
| Full Idea: Should necessity be treated as a predicate rather than (as in modal logic) as a sentential operator? It is odd to assign different status to necessity and truth, hampering their interaction. That all necessities are true can't be expressed by an operator. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 24.2) | |
| A reaction: [compressed] Halbach and Horsten consistently treat truth as a predicate, but maybe truth is an operator. Making necessity a predicate and not an operator would be a huge upheaval in the world of modal logic. Nice move! |
| 6600 | The belief that fire burns is like the fear that it burns [Wittgenstein] |
| Full Idea: The belief that fire will burn me is of the same kind as the fear that it will burn me. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §473) | |
| A reaction: Most of our beliefs are forced on us, rather than chosen, and this nice remark gives an indication of the reason. It dovetails with Peirce's pragmatic approach to be belief (e.g. Idea 6598), which is well developed by Robert Fogelin. |
| 4153 | Are sense-data the material of which the universe is made? [Wittgenstein] |
| Full Idea: Are sense-data the material of which the universe is made? | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §401) | |
| A reaction: Presumably the question is meant to be absurd, and to a realist it is. You can't serious think that a filing cabinet is made of sensations. |
| 6501 | As sense-data are necessarily private, they are attacked by Wittgenstein's objections [Wittgenstein, by Robinson,H] |
| Full Idea: Sense-data are usually conceived as necessarily private to individual observers, so the final crisis for the empiricist conception of perception was Wittgenstein's famous polemic against such private objects. | |
| From: report of Ludwig Wittgenstein (Philosophical Investigations [1952]) by Howard Robinson - Perception IV.1 | |
| A reaction: Personally I remain unconvinced by Wittgenstein's very elusive argument, but I think there are plenty of other reasons for doubting whether the idea of sense-data throws much light on our understanding of the processes of perception. |
| 11079 | How do I decide when to accept or obey an intuition? [Wittgenstein] |
| Full Idea: If intuition is an inner voice - how do I know how I am to obey it? And how do I know that it doesn't mislead me? For if it can guide me right, it can also guide me wrong. ((Intuition an unnecessary shuffle)) | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], 213) | |
| A reaction: Presumably the last point, in brackets, means that you still have to evaluate the intuition, with which I would agree. I take judgement to occur in the space of reasons, to which intuition is a major contributor. Only a fool would just accept intuition. |
| 4160 | One can mistrust one's own senses, but not one's own beliefs [Wittgenstein] |
| Full Idea: One can mistrust one's own senses, but not one's own beliefs. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], II.x) | |
| A reaction: This seems right, because we don't choose our beliefs. We don't even choose whether to believe a sensation - we just focus harder until belief does or doesn't occur. |
| 19273 | I don't have the opinion that people have minds; I just treat them as such [Wittgenstein] |
| Full Idea: My attitude towards him is an attitude towards a soul. I am not of the 'opinion' that he has a soul. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], II.iv) | |
| A reaction: This seems to be precisely Dennett's 'intentional stance', where we conjure up minds in things like chess-playing computers, irrespective of whether we believe they are conscious. |
| 5663 | It is irresponsible to generalise from my own case of pain to other people's [Wittgenstein] |
| Full Idea: If I say of myself that it is only from my own case that I know what the word 'pain' means - must I not say the same of other people too? And how can I generalise from the one case so irresponsibly? | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §293) | |
| A reaction: This is the best known objection to Mill's Argument from Analogy for other minds. It appears to be induction from a single instance. The better approach seems to be ABduction (best explanation), in which my own case is just some evidence. |
| 19272 | To imagine another's pain by my own, I must imagine a pain I don't feel, by one I do feel [Wittgenstein] |
| Full Idea: If one has to imagine someone else's pain on the model of one's own, this is none too easy a thing to do: for I have to imagine pain which I do not feel on the model of pain which I do not feel. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §302) | |
| A reaction: I just don't feel a deep problem here. Wittgenstein didn't know about mirror neurons, which trigger in me a reaction like the one causing your behaviour. |
| 4161 | If a lion could talk, we could not understand him [Wittgenstein] |
| Full Idea: If a lion could talk, we could not understand him. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], II.xi) | |
| A reaction: How does he know these things?! We could at least know whether they talked or merely grunted, by studying their correlated behaviour. Cf. dolphins. I think he is wrong. All talk is understandable to a degree, even God's. |
| 7392 | If a lion could talk, it would be nothing like other lions [Dennett on Wittgenstein] |
| Full Idea: I think that if a lion could talk, that lion would have a mind so different from the general run of lion minds, that although we could understand him just fine, we would learn little about ordinary lions from him. | |
| From: comment on Ludwig Wittgenstein (Philosophical Investigations [1952], II.xi) by Daniel C. Dennett - Consciousness Explained 14.2 | |
| A reaction: This is rather more sensible than Wittgenstein's famous enigmatic utterance. |
| 5676 | To say that I 'know' I am in pain means nothing more than that I AM in pain [Wittgenstein] |
| Full Idea: As the word is normally used, it can't be said of me at all that I 'know' I am in pain; what is it supposed to mean - except perhaps that I am in pain? | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §246) | |
| A reaction: This raises the question of whether self-consciousness implies self-knowledge, and suggests that it doesn't. All our normal talk of knowledge requires some sort of reliable justification of beliefs, and we can't drop that in the case of self-knowledge. |
| 4154 | Why are we not aware of the huge gap between mind and brain in ordinary life? [Wittgenstein] |
| Full Idea: Why does the feeling of an unbridgeable gulf between consciousness and brain-process not come into the considerations of our ordinary life? | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §412) | |
| A reaction: Nice question. Presumably Wittgenstein has a quasi-behaviouristic answer. People don't now ignore it? They retreat into crazy spiritualism. |
| 6165 | Every course of action can either accord or conflict with a rule, so there is no accord or conflict [Wittgenstein] |
| Full Idea: Paradox: no course of action could be determined by a rule, because every course of action can be made out to accord with the rule. Answer: if everything can accord with the rule, then everything can conflict with it, so there is no accord or conflict. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §201) | |
| A reaction: This is a very interesting claim which goes beyond the private language question. It seems to imply, for example, Dancy's 'Particularism' about morality, which is a general rejection of rules and principles in moral thought. |
| 4143 | One cannot obey a rule 'privately', because that is a practice, not the same as thinking one is obeying [Wittgenstein] |
| Full Idea: 'Obeying a rule' is a practice. And to think one is obeying a rule is not to obey a rule. Hence it is not possible to obey a rule 'privately': otherwise thinking one was obeying a rule would be the same thing as obeying it. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §202) | |
| A reaction: The core of the Private Language argument. But if I drive on the right erroneously thinking it is the law, I can still make progress until I meet someone. |
| 7092 | If individuals can't tell if they are following a rule, how does a community do it? [Grayling on Wittgenstein] |
| Full Idea: The problem facing a putative private language-user - namely, that he cannot tell whether he is, or only thinks he is, following a rule - also faces the community as a whole; how does the community tell whether it is following a rule? | |
| From: comment on Ludwig Wittgenstein (Philosophical Investigations [1952], §580) by A.C. Grayling - Wittgenstein Ch.3 | |
| A reaction: Nice question. If you really get into the sceptical frame of mind that Wittgenstein reached about rules, almost everything seems impossible. How can I move? How can I speak? How can one instant follow another? How can I understand a word? |
| 4158 | An 'inner process' stands in need of outward criteria [Wittgenstein] |
| Full Idea: An 'inner process' stands in need of outward criteria. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §580) | |
| A reaction: Why do processes need 'criteria'? I have never understood why I can't have private criteria, or at least private modifications of public criteria. |
| 4138 | Is white simple, or does it consist of the colours of the rainbow? [Wittgenstein] |
| Full Idea: Is white simple, or does it consist of the colours of the rainbow? | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §047) | |
| A reaction: A nice challenge to externalism. White remains simple long after experts have told us it is complex. |
| 7055 | Externalist accounts of mental content begin in Wittgenstein [Wittgenstein, by Heil] |
| Full Idea: The roots of externalist accounts of mental content lie in Wittgenstein. | |
| From: report of Ludwig Wittgenstein (Philosophical Investigations [1952]) by John Heil - From an Ontological Point of View 18.2 n1 | |
| A reaction: This points to the key idea being that content involves the whole language community, rather than that it involves the physical stuffs of the world, such as water. I suspect that Wittgenstein is right, but Putnam is wrong. |
| 12576 | Possessing a concept is knowing how to go on [Wittgenstein, by Peacocke] |
| Full Idea: Wittgenstein implies that which concepts a thinker is capable of possessing depends on the ways in which he is capable of finding a natural way to go on. | |
| From: report of Ludwig Wittgenstein (Philosophical Investigations [1952]) by Christopher Peacocke - A Study of Concepts 1.2 | |
| A reaction: This doesn't seem to amount to much. Presumably someone who failed to grasp a concept would demonstrate the fact by going on in a silly way, and whether or not it was silly might not be obvious. A genius may go on in a quirky way. |
| 4157 | Concepts direct our interests and investigations, and express those interests [Wittgenstein] |
| Full Idea: Concepts lead us to make investigations; are the expression of our interest, and direct our interest. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §570) | |
| A reaction: This presumably points to the evolutionary origin of our concept-creating capacity, though I am not sure that it defines what a concept actually is. |
| 12606 | Man learns the concept of the past by remembering [Wittgenstein] |
| Full Idea: Man learns the concept of the past by remembering. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], II.13) | |
| A reaction: [quoted by Peacocke] Is it the case that we learn all of our concepts by doing? Obviously not, since we can be taught them. Could you have no long-term memories (head trauma), and be taught the concept of the past by someone else? |
| 4141 | Various games have a 'family resemblance', as their similarities overlap and criss-cross [Wittgenstein] |
| Full Idea: I shall say 'games' form a family, with a 'family resemblance', for the resemblances within a family - build, eyes, temperament etc. - overlap and criss-cross in the same way. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §067) | |
| A reaction: A very helpful idea for the nominalist view of universals, particularly for showing how concepts shade off indeterminately at the edges. |
| 23450 | Wittgenstein rejected his earlier view that the form of language is the form of the world [Wittgenstein, by Morris,M] |
| Full Idea: Wittgenstein's later work rejects the central thesis of the Tractatus's philosophy of language, that the form of language is the same as the form of the world. | |
| From: report of Ludwig Wittgenstein (Philosophical Investigations [1952]) by Michael Morris - Guidebook to Wittgenstein's Tractatus Intro.4 | |
| A reaction: I associate the earlier view with the stoic belief that nature is wholly rational, and that our reasoning can match it. I take it for granted that language largely matches the world, but we must explain why so many people believe absurdities. |
| 4150 | Asking about verification is only one way of asking about the meaning of a proposition [Wittgenstein] |
| Full Idea: Asking whether and how a proposition can be verified is only a particular way of asking 'How do you mean?' The answer is a contribution to the grammar of the proposition. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §353) | |
| A reaction: 'How' a proposition is verified seems utterly irrelevant. What situation in reality provides the verification must have something to do with the meaning. Cat-on-mat is what counts, not whether you see it, hear it or smell it. |
| 4137 | In the majority of cases the meaning of a word is its use in the language [Wittgenstein] |
| Full Idea: For a large class of cases - though not for all - the meaning of a word is its use in the language. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §043) | |
| A reaction: Defended by Paul Horwich, but I don't like this. If "swordfish" is a password, its meaning and its use are miles apart. Meaning connects to reality, but use doesn't. |
| 6567 | For Wittgenstein, words are defined by their use, just as chess pieces are [Wittgenstein, by Fogelin] |
| Full Idea: For Wittgenstein, just as pieces in a game such as chess are defined by the rules that govern their moves, the meanings of words are similarly defined by the rules that govern their employment. | |
| From: report of Ludwig Wittgenstein (Philosophical Investigations [1952]) by Robert Fogelin - Walking the Tightrope of Reason Ch.2 | |
| A reaction: Fogelin's note points out that it is more complex than this. It is hard to dispute the chess case, but while words like 'and' and 'not' may be given entirely functional definitions, others don't work like that: John, run, red, solid, pain, ow! …. |
| 6169 | We do not achieve meaning and understanding in our heads, but in the world [Wittgenstein, by Rowlands] |
| Full Idea: For Wittgenstein, meaning and understanding are not things that we do or achieve in our heads; they are things we achieve in the world. | |
| From: report of Ludwig Wittgenstein (Philosophical Investigations [1952], §202) by Mark Rowlands - Externalism Ch.5 | |
| A reaction: Can't we achieve anything in our heads? Mental arithmetic seems to be fairly mental, unless we are going to be absurdly behaviouristic. If we can achieve some things in our heads, why not lots of things? |
| 4155 | We all seem able to see quite clearly how sentences represent things when we use them [Wittgenstein] |
| Full Idea: It it be asked, "How do sentences manage to represent?" the answer might be, "Don't you know? You certainly see it when you use them." For nothing is concealed. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §435) | |
| A reaction: A tool isn't its use, even though it becomes obvious how a tool works when it is used. It has a use because it has a certain nature or property. |
| 4142 | To understand a sentence means to understand a language [Wittgenstein] |
| Full Idea: To understand a sentence means to understand a language. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §198) | |
| A reaction: Does this make learning a language logically impossible? Helen Keller only knew one word at the beginning. |
| 4149 | We don't have 'meanings' in our minds in addition to verbal expressions [Wittgenstein] |
| Full Idea: When I think in language, there aren't 'meanings' going through my mind in addition to the verbal expressions. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §329) | |
| A reaction: No, but words have properties, like being meaningful, or long, or beautiful. They are not abstractions, or empty counters which can be used for anything. |
| 4156 | Make the following experiment: say "It's cold here" and mean "It's warm here" [Wittgenstein] |
| Full Idea: Make the following experiment: say "It's cold here" and mean "It's warm here". | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §510) | |
| A reaction: A lovely experiment, whatever it proves. It is easier if the meaning is the truth, rather than the words. I try to weld a new word onto my experience. |
| 4145 | How do words refer to sensations? [Wittgenstein] |
| Full Idea: How do words refer to sensations? | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §244) | |
| A reaction: A very nice question, to be remembered when discussing how we refer to beauty, gold, water or the present King of France. |
| 4140 | The standard metre in Paris is neither one metre long nor not one metre long [Wittgenstein] |
| Full Idea: There is one thing of which one can say neither that it is one metre long, nor that it is not one metre long, and that is the standard metre in Paris. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §050) | |
| A reaction: The remark which inspired Kripke's causal theory. Clearly W. is wrong, because it is one metre long, but why is it that length? |
| 16298 | We need propositions to ascribe the same beliefs to people with different languages [Halbach] |
| Full Idea: Being able to ascribe the same proposition as a belief to persons who do not have a common language seems to be one of the main reasons to employ propositions. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 2) | |
| A reaction: Propositions concern beliefs, as well as sentence meanings. I would want to say that a dog and I could believe the same thing, and that is a non-linguistic reason to believe in propositions. Maybe 'translation' cuts out the proposition middleman? |
| 4136 | To imagine a language means to imagine a form of life [Wittgenstein] |
| Full Idea: To imagine a language means to imagine a form of life. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §019) | |
| A reaction: I take this to be about the transparency of language, but it supports meaning as truth conditions, rather than as use. |
| 6166 | Was Wittgenstein's problem between individual and community, or between occasions for an individual? [Rowlands on Wittgenstein] |
| Full Idea: There are two interpretations of Wittgenstein here: the community interpretation sees error in a rule between the individual and the community, where the individual interpretation sees the problem between repeated occasions in the use of a sign. | |
| From: comment on Ludwig Wittgenstein (Philosophical Investigations [1952], §202) by Mark Rowlands - Externalism Ch.5 | |
| A reaction: Rowlands brings out how a lot hangs on which of these two interpretations we opt for, but also that if the individual has a problem, this may logically imply the same problem for the community. The individual interpretation would be a deeper problem. |
| 7875 | If a brilliant child invented a name for a private sensation, it couldn't communicate it [Wittgenstein] |
| Full Idea: Let's assume the child is a genius and itself invents a name for the sensation! - But then, of course, he couldn't make himself understood when he used the word. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §257) | |
| A reaction: [His example is a sensation with no behaviour] Sensations are not just related to behaviour; they are related to external objects, and to parts of the body. We doubt the sensations of others if they can't name the object or the body part. |
| 4146 | We cannot doublecheck mental images for correctness (or confirm news with many copies of the paper) [Wittgenstein] |
| Full Idea: If the mental image of a train timetable cannot itself be tested for correctness, how can it confirm the correctness of the first memory? (As if someone were to buy several copies of the morning paper to assure himself that what it said was true). | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §265) | |
| A reaction: An important point for the epistemological sceptic. Could God do an infinite regress of checks on the truth of his mental images? |
| 4147 | If we only named pain by our own case, it would be like naming beetles by looking in a private box [Wittgenstein] |
| Full Idea: If someone says he only knows what pain is from his own case, suppose everyone had a box with something in it (a 'beetle'). We can't see into other boxes, so we say what a beetle is by looking in our own box. The contents of each box could be different. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §293) | |
| A reaction: But pain is private. Children must guess the meaning of parts of the language that refer to inner experience, like 'sad' or 'hopeful'. Body language brings our private concepts together, but error seems possible. |
| 5659 | If the reference is private, that is incompatible with the sense being public [Wittgenstein, by Scruton] |
| Full Idea: Wittgenstein's claim is that the assumption that the reference is private (being observable to one person alone) is incompatible with the hypothesis that the sense is public. | |
| From: report of Ludwig Wittgenstein (Philosophical Investigations [1952], §293) by Roger Scruton - Short History of Modern Philosophy Ch.19 | |
| A reaction: An illuminating summary, showing the link between the private language argument and modern 'externalism' about the meaning of concepts (e.g. Idea 4099). I still don't find Wittgenstein's claim conclusive. Something is definitely private. |
| 4152 | Getting from perceptions to words cannot be a private matter; the rules need an institution of use [Wittgenstein] |
| Full Idea: I could not apply any rules to a private transition from what is seen to words. Here the rules really would hang in the air; for the institution of their use is lacking. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §380) | |
| A reaction: That puts the argument nicely. In studying art or wine you learn what to say about your private experiences. |
| 4144 | Common human behaviour enables us to interpret an unknown language [Wittgenstein] |
| Full Idea: The common behaviour of mankind is the system of reference by means of which we interpret an unknown language. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §206) | |
| A reaction: This is a behaviourist spin on the idea of charity, but it leads to Davidson's assumption that most alien beliefs must be true. |
| 11049 | To communicate, language needs agreement in judgment as well as definition [Wittgenstein] |
| Full Idea: If language is to be a means of communication there must be agreement not only in definitions but also (queer as this may sound) in judgments. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §242) | |
| A reaction: If someone is locked into a highly alien viewpoint, then communication with them does seem to be virtually impossible. Amenability to reason, and consensus on elementary facts, seems to be the sine qua non of communication. |
| 6658 | What is left over if I subtract my arm going up from my raising my arm? [Wittgenstein] |
| Full Idea: What is left over if I subtract the fact that my arm goes up from the fact that I raise my arm? | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §621) | |
| A reaction: Wittgenstein's implication seems to be that nothing is left over, but I would have thought that the will was the thing left over when you decide to raise your arm, but then discover that you are paralysed. |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| Full Idea: Archelaus was the first person to say that the universe is boundless. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 02.Ar.3 |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |
| Full Idea: Archelaus wrote that life on Earth began in a primeval slime. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Malcolm Schofield - Archelaus | |
| A reaction: This sounds like a fairly clearcut assertion of the production of life by evolution. Darwin's contribution was to propose the mechanism for achieving it. We should honour the name of Archelaus for this idea. |
| 4151 | Grammar tells what kind of object anything is - and theology is a kind of grammar [Wittgenstein] |
| Full Idea: Grammar tells what kind of object anything is. (Theology as grammar) | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], §373) | |
| A reaction: A classic twentieth century blunder, originating in Frege and culminating in Quine, of thinking that the analysis of language is the last word in ontology. |
| 4159 | The human body is the best picture of the human soul [Wittgenstein] |
| Full Idea: The human body is the best picture of the human soul. | |
| From: Ludwig Wittgenstein (Philosophical Investigations [1952], II.iv) | |
| A reaction: Nice. How did we imagine the soul before reading that remark? My soul requires fingernails and eyelids in order to fulfil its essential nature. |